Technical Field
The present invention relates to a bearing structure and, for example, to a bearing structure for a crankshaft in a multi-link-type piston crank mechanism.
Related Art
For example, in a patent document 1, as a piston crank mechanism in an internal combustion engine, there is disclosed a multi-link-type piston crank mechanism having a lower link supported by the crank pin of a crankshaft, an upper link connecting the one end portion of the lower link to a piston pin, and a control link connecting the other end portion of the lower link to the eccentric shaft part of a control shaft.
In such a multi-link-type piston crank mechanism, a crankshaft and a control shaft are required to be rotatably supported individually. The patent document 1 discloses a bearing structure where the crankshaft is supported between the bulkhead of a cylinder block and a main bearing cap, and a control shaft bearing cap is attached to the underside of the main bearing cap, and the control shaft is supported between the main bearing cap and the control shaft bearing cap.
In addition, the control shaft bearing cap has a bearing beam structure in which a plurality of bearing caps are connected in a ladder form by a beam part extending in an engine longitudinal direction, and is configured to supply lubricating oil to the control shaft bearing part from an oil gallery formed in the beam part.
However, for the configuration as in patent document 1 in which the lubricating oil is supplied to the control shaft bearing part through the inside of the beam part, it may be necessary to form the control shaft bearing cap in the bearing beam structure, thereby leading to a low flexibility of design.
Patent Document 1: Japanese Patent Application Publication 2004-116434